1. Field of the Invention
The present invention relates to a power line channel-adaptive communications system and method.
2. Description of the Related Art
In general, the characteristics of a power line channel are greatly influenced by not only signal attenuation depending on the distance, but noise generated by indoor electrical appliances, information household appliances and office equipment. In particular, it can be said that a power line channel has a poor channel state in a low frequency band as compared with that in other frequency bands.
Since a chirp band spread modulation and demodulation technology has the characteristic of the linear time-frequency modulation of transmission signals, it provides stable communication performance despite noise occurring in the power line and variation in the channel impedance. In the transmission of a chirp band spread signal, when a transmission symbol signal is extended using the frequency linearity of the transmission symbol signal, the data transmission rate can be further increased, and a synchronization unit capable of more easily obtaining the data of received signals can be implemented.
However, since high-load electrical equipment with a larger noise source is coupled to a power line network, the SNR of the received signal level against the noise level in the power line is subject to sharp decreases, so that there may be a problem with communication connectivity or communication reliability. For this reason, reliable data cannot be transmitted using only the chirp band spread method, so that there is a need for an additional scheme capable of compensating for the problem because.